Casings for electric connections are known from EP443694, U.S. Pat. No. 5,828,005, U.S. Pat. No. 6,265,665, U.S. Pat. No. 5,397,859 and U.S. Pat. No. 4,859,809. These documents disclose a casing for electric connections comprising two elements which can be reciprocally coupled in a reversible or irreversible manner and delimiting an internal cavity for a terminal box or similar device and a plurality of in/out openings for one or more cables which can be connected to the terminal box or similar device. The internal space of at least one of said two elements is filled with dielectric gel which occupies said space before the positioning of the terminal box or similar device into said cavity, that is to say it is provided with a predetermined quantity of dielectric gel which occupies its internal space.